Detect if PHP session exists

Question

Facebook now offer subscriptions to users so you can get realtime updates on changes. If my app receives an update, I plan to store it in the database. I would also like to

Answer 1

If you are on php 5.4+, it is cleaner to use session_status():

if (session_status() == PHP_SESSION_ACTIVE) {
  echo 'Session is active';
}

• PHP_SESSION_DISABLED if sessions are disabled.
• PHP_SESSION_NONE if sessions are enabled, but none exists.
• PHP_SESSION_ACTIVE if sessions are enabled, and one exists.

Answer 2

function is_session_started()
{
    if ( php_sapi_name() !== 'cli' ) {
        if ( version_compare(phpversion(), '5.4.0', '>=') ) {
            return session_status() === PHP_SESSION_ACTIVE ? TRUE : FALSE;
        } else {
            return session_id() === '' ? FALSE : TRUE;
        }
    }
    return FALSE;
}

// Example
if ( is_session_started() === FALSE ) session_start();

Answer 3

Which method is used to check if SESSION exists or not? Answer: isset($_SESSION['variable_name'])

Example: isset($_SESSION['id'])

Answer 4

According to the PHP.net manual:

If $_SESSION (or $HTTP_SESSION_VARS for PHP 4.0.6 or less) is used, use isset() to check a variable is registered in $_SESSION.

Answer 5

I use a combined version:

if(session_id() == '' || !isset($_SESSION)) {
    // session isn't started
    session_start();
}